How a big US bank laundered billions from Mexico’s murderous drug gangs

As the violence spread, billions of dollars of cartel cash began to seep into the global financial system. But a special investigation by the Observer reveals how the increasingly frantic warnings of one London whistleblower were ignored

On 10 April 2006, a DC-9 jet landed in the port city of Ciudad del Carmen, on the Gulf of Mexico, as the sun was setting. Mexican soldiers, waiting to intercept it, found 128 cases packed with 5.7 tons of cocaine, valued at $100m. But something else – more important and far-reaching – was discovered in the paper trail behind the purchase of the plane by the Sinaloa narco-trafficking cartel.

During a 22-month investigation by agents from the US Drug Enforcement Administration, the Internal Revenue Service and others, it emerged that the cocaine smugglers had bought the plane with money they had laundered through one of the biggest banks in the United States: Wachovia, now part of the giant Wells Fargo.

The authorities uncovered billions of dollars in wire transfers, traveller’s cheques and cash shipments through Mexican exchanges into Wachovia accounts. Wachovia was put under immediate investigation for failing to maintain an effective anti-money laundering programme. Of special significance was that the period concerned began in 2004, which coincided with the first escalation of violence along the US-Mexico border that ignited the current drugs war.